It's usually a teenager with a sob story about poverty, talking about a special program he is in to help improve himself, etc. This time, it was some bogus program called the STEP program. They usually claim that if you donate money or buy magazines or whatever it is that they are selling this month, they can earn points to go to college or go to Europe or pay for an operation or whatever BS they can think of.
He makes sure to let you know that he notices your family is at home, and that he wishes safety for all of them, so that he can plant a little seed of subconscious fear in you.
If the appeal for your Palo Alto liberal ideals fails, he appeals to your other qualities...i.e. your hypocritical fear of people from bad neighborhoods. He starts to act agitated. He starts to say "What?! You don't want to help keep me away from gangs and drugs?!"
Pretty soon, he has you on the defensive, and you are feeling very uncomfortable, and willing to do anything to get them to leave, i.e. give them money.
Words of advice:
1. Do not open the doors to solicitors.
2. If you do open the door, never let them in your house. They may ask to use your restroom or ask for a glass of water. Never let them in, or they will not leave until you give them money. Or they may leave with your jewelry.
3. Tell them you are not interested over and over until they leave. Do not engage in any debates with them. Do not answer questions that are intended to trap you into further discussions, e.g. "Don't you want to help me go to college?"
If enough Palo Altans stop giving to these scam artists, then they will stop harassing us.